Reply #42: Ok, you are talking about an older engine

[Mopar151]

Are you talking about the 229 Chevy or the 231 Buick? My bad - basically, tin covers tend to leak anyway. Retorquing will make them leak WORSE over time, and will require them to be straightened when gaskets are finally replaced. if the bolts are backing off, self-locking fasteners are necessary.

Exhaust manifolds too close to the valve cover rail are a big problem, too - old 440 Mopahs will toast the gaskets until they crack, then leak onto the hot spot Noice!